PROJECT SUMMARY RESEARCH PROJECT 1 Project 1 will elucidate how the networks of antigen presenting cells (APCs) in the human lung regulate immunity to respiratory viruses. The goal is to also explain how microbiome-driven lung inflammation or inflammation that is linked with neoplastic processes affects such responses. Project 1 is founded on the scientific premise that identifying the pathways underpinning immune cell responses to respiratory viruses in situ is key to identifying targets and strategies for designing and developing improved vaccines. Our overall hypothesis is that the lung environment defines immunological status, i.e., the ?immune set-point?, and the function of tissue-resident dendritic cells (DCs). We further posit that the immune set-point impacts the fate of antigen and the quality and magnitude of ensuing mucosal T-cell immunity. Implicit in this hypothesis is a role for the local microbiome, which we predict contributes to the immediate environment by direct and indirect crosstalk with immune cells and ensuing inflammatory responses. We propose three aims: Aim 1 will test the hypothesis that steady state cellular and molecular networks in human lung tissue regulate the early response to respiratory viruses. We will define the composition and functional status of human lung tissue across a range of clinical situations: normal lung, uninvolved cancer patient lung and cancer-involved lung tissue. Correlative analyses with upstream environmental regulators such as the microbiome will identify pathways that control the magnitude and quality of ensuing adaptive immunity. Aim 2 will test the hypothesis that the generation of anti-viral T-cell immunity is modulated by lung epithelial cell (EC)-DC crosstalk and that this crosstalk is further modulated by commensal bacteria. We will determine how lung DCs exposed to virally-infected lung alveolar epithelial cells (AECs) modulate the differentiation of T cells; we will establish the molecular programs in DCs triggered by lung ECs that can explain T-cell phenotypes; and we will determine how the bacteria cultured from the mouth and upper respiratory tract impacts lung ECs and downstream responses. Aim 3 will test the hypothesis that the lung microenvironment modulates the cross-presentation capacity of lung-resident APCs thereby dictating the fate of viral antigen-specific CD8+ T cells. We will assess viral distribution and cross-presentation in the context of resistant and susceptible cells defined by expression of a viral resistance gene, Rab15; and the access of opsonized virus to cross-presenting compartments in lung myeloid cells. Thus, this project will elucidate the key innate immune networks that determine the overall outcome of adaptive immune responses during respiratory viral infections. Along with other Projects, our proposed research has a high potential to discover novel target molecules that will eventually help us design improved therapeutics and vaccines for respiratory infections. Finally, the work proposed here will guide development and validation of 3D printed lung tissues, which will enable genetic experiments and possibly future studies on human tissue immunity.